(Samuel 1972: 1)

The concept of a "day" raises another dilemma in the creation of calendars. The cycle of sunrises and sunsets appears an obvious choice for demarcating periods of time. The 24 hour period is based on the amount of time the earth requires to complete a single revolution; but the duration of the earth's orbit is not perfectly divisible by 24, which is why a year lasts 365.25 days. A unit slightly longer than 24 hours would make a better "day," with respect to achieving absolute seasonal consistency. A longer "day," however, would eliminate the consistency between days-- the planet would revolve slightly more by a given time on each subsequent day.